The Q2 dependence of the structure function ratio F2Sn/F2C for 0.01 < x < 0.75 and 1 < Q2 < 140 GeV2 is reported. For x < 0.1 the size of shadowing decreases with ln Q2 and the maximum rate is about 0.04 at x = 0.01. The rate decreases with x and is compatible with zero for x ⩾ 0.1. The difference RSn − RC, where R is the ratio of longitudinally to transversely polarised virtual photon absorption cross sections, is also given. No dependence on x is seen and the average value is 0.040 ± 0.021 (stat.) ± 0.026 (syst.) at a mean Q2 of 10 GeV2.
